Fix RedundantOverride error flagged by error prone

Running recent error prone version complaining on that code:

XAuthFilter.java:81: error: [RedundantOverride] This overriding method
is redundant, and can be removed.
    public PrintWriter getWriter() throws IOException {
                       ^
    (see https://errorprone.info/bugpattern/RedundantOverride)
  Did you mean to remove this line?

Bug: Issue 12677
Change-Id: Ia0712501bb0aafed669f1d713ca9bbb57c81d236
diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java b/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
index 616b9a4..cbdf6e1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/XAuthFilter.java
@@ -22,7 +22,6 @@
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import java.io.IOException;
-import java.io.PrintWriter;
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
@@ -78,11 +77,6 @@
             }
 
             @Override
-            public PrintWriter getWriter() throws IOException {
-              return super.getWriter();
-            }
-
-            @Override
             public ServletOutputStream getOutputStream() throws IOException {
               return new TokenReplaceOutputStream(
                   (HttpServletResponse) getResponse(),